Efficient mitochondrial targeting relies on co-operation of multiple protein signals in plants
Efficient mitochondrial targeting relies on co-operation of multiple protein signals in plants
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DOI：
10.1093/jxb/ern319
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发表时间：
2009-03-01
影响因子：
6.9
通讯作者：
Brandizzi, Federica
中科院分区：
文献类型：
--
作者：
Chatre, Laurent;Matheson, Loren A.;Brandizzi, Federica
到目前为止，最流行的将前蛋白运输到植物线粒体的模型是基于作为靶向多肽的N末端延伸的活性。蛋白质向线粒体的有效输送是完全基于N-末端延伸的作用，还是也基于其他蛋白质决定因素的作用，目前还没有确定。这里报道了一种新的机制，将一种名为MITS1的植物蛋白靶向线粒体。研究发现，MITS1含有一个负责线粒体靶向的N-末端延伸。对这一延伸的功能剖析表明，存在一个针对分泌途径的蛋白质的隐蔽信号。N末端延伸的前11个氨基酸是克服该信号序列的活性并将蛋白质靶向线粒体所必需的。这些数据表明，对于有效的线粒体靶向来说，线粒体蛋白质N端延伸内的多个决定因素的合作可能是必要的。还证实了蛋白质C末端色氨酸残基的存在对于线粒体靶向是至关重要的，因为该残基的突变导致MITS1重新分布到内质网和高尔基体。这些数据表明了一种新的靶向模型，在该模型中，蛋白质到植物线粒体的运输受到全长蛋白质中的结构域以及N-末端延伸的影响。
To date, the most prevalent model for transport of pre-proteins to plant mitochondria is based on the activity of an N-terminal extension serving as a targeting peptide. Whether the efficient delivery of proteins to mitochondria is based exclusively on the action of the N-terminal extension or also on that of other protein determinants has yet to be defined. A novel mechanism is reported here for the targeting of a plant protein, named MITS1, to mitochondria. It was found that MITS1 contains an N-terminal extension that is responsible for mitochondrial targeting. Functional dissection of this extension shows the existence of a cryptic signal for protein targeting to the secretory pathway. The first 11 amino acids of the N-terminal extension are necessary to overcome the activity of this signal sequence and target the protein to the mitochondria. These data suggest that co-operation of multiple determinants within the N-terminal extension of mitochondrial proteins may be necessary for efficient mitochondrial targeting. It was also established that the presence of a tryptophan residue toward the C-terminus of the protein is crucial for mitochondrial targeting, as mutation of this residue results in a redistribution of MITS1 to the endoplasmic reticulum and Golgi apparatus. These data suggest a novel targeting model whereby protein traffic to plant mitochondria is influenced by domains in the full-length protein as well as the N-terminal extension.